The present invention relates to a data processing technology for making a data replication.
In an online work that conducts a lot of transactions, aggregation of a large amount of data, which requires daily or monthly operations, and the like, are obstructive to a 24-hour continuous operation. In other words, the batch processing for these works, which involves a batch access to the data base that is used in the online work, has a considerable effect on online work processing.
As a solution thereof, a method is known, as disclosed in for example JP-A-2000-347811, in which a plurality of data management systems are placed on LAN (Local Area Network)/WAN (Wide Area Network), and an update content of the data base which is used in the online work is always transmitted and copied to another data base management system via a network, thus a replication of a data base for the online work being provided. It is possible to prevent burdens from falling on the online work side too much and to conduct the online work in parallel with batch processing by performing the foregoing batch processing on the replication data base side.
Another method is also known which utilizes a SAN (Storage Area Network) configuration, which has become widespread in recent years for general storage devices, or a configuration in which a plurality of external storage devices, such as a magnetic disc device and the like, are organically connected via a dedicated high speed network, to provide a replication (or may be referred to as a replica, a snap shot, or a shadow image) of the data base for the online work.
In the configuration, the external storage device, such as a storage device or the like, provides: a function of copying rapidly an arbitrary logical volume to a plurality of logical volumes; a function of performing multiple write of data assuming the arbitrary logical volume as an original volume and the plurality of logical volumes as a duplicate volume; a function of separating the logical volumes which are in a state of multiple write at an arbitrary point in time to allow the volumes to be accessed as an independent original or duplicate volume; and the like. In the data base replication created in such a scheme, the data base is copied to the data base replication based on a certain arbitrary time when the pair of the original and duplicate volumes was released. Therefore, transactions, which were conducted before that release time, are copied to the data base replication in an updated state.